The invention relates to improvements in centrifugal separators for separating solid-liquid mixtures into a liquid fraction and a heavier fraction. More particularly, the invention relates to improvements in a centrifuge drum which is rotatable about a longitudinal axis and has therein a conveyor worm which rotates at a different speed and the material to be separated is discharged along the axis of the drum and separate openings are provided for the discharge of the separated light and separated heavy substances.
In the field of this development, German Published Application 33 17 047 discloses a cylindrical solid bowl worm centrifuge of the above general type for separating suspensions. This centrifuge includes a separating disk at one end of the separating space that provides an annular gap between the disk and the drum. Clear phase channels that discharge into a clear phase discharge line are radially arranged at the worm member at a distance preceding the separating disk. A sediment channel proceeds radially and is arranged immediately following the separating disk. This sediment channel discharges into a sediment discharge line that is coaxially arranged relative to the clear phase discharge line. This known structure provides disadvantages in that it can be only utilized for separating thin bodied agents due to the risk of occluding the discharge channels. Over and above this, the material has to be supplied to the centrifuge pressure and the centrifuge can be operated only under pressure. In order to accomplish this, the centrifuge must be provided with special seals, particularly axial face seals both in the material admission region as well as in the discharge region where the agents are separated from one another. These seals not only have to be frequently changed because of rapid wear but are relatively complicated in structure which involves a high initial cost. Further, the liquid discharges through the hollow centrifugal shaft and thereby requires a special hollow shaft gearing for the worm drive. This is relatively complicated and costly. A solid bowl worm centrifuge is disclosed in U.S. Pat. No. 4,566,873 and is basically identically fashioned and is disadvantageous in the same manner.
It is accordingly an object of the present invention to provide a solid bowl worm centrifuge which avoids the above disadvantages of structures heretofore available. A further object of the invention is to provide an improved solid bowl worm centrifuge which is unique in having a simple structural format and is particularly advantageous in having extremely low energy consumption relative to the high separation ability and enables continuous separation of solid-liquid mixtures.